1. Field of the Invention:
This invention relates to a magnetic disc apparatus and a method of manufacturing the magnetic disc apparatus. More particularly the invention is directed to an improvement to the structure of a magnetic head for such an apparatus.
2. Description of the Related Art:
Because they are capable of recording of a large quantity of data and also enable a random access, magnetic disc drives have hitherto been performing the central part in file memories of data processing systems and computer systems. Practically, the main performance of a magnetic disc drive is evaluated from the recording density and the mean access time (time necessary to locate a magnetic head in a predetermined track). This mean access time is proportional to the square root of mass of a movable member and hence can be shortened by reducing the mass of the movable member. The more the magnetic head moves closer to a magnetic recording medium surface, the higher the recording density and the larger the output can be obtained.
FIGS. 8 and 9 of the accompanying drawings are a side elevational view of a conventional bulk flying magnetic head apparatus and a side elevational view of a conventional thin film flying magnetic head apparatus, respectively, which are disclosed, for example, in Journal of The Japan Society of Mechanical Engineers, volume 87, No. 791, issued on October 1984. Similar flying head slider is further disclosed in Japanese Patent Publication No. 21329/1983. In FIGS. 8 and 9, the conventional flying magnetic head apparatus generally comprises a magnetic recording medium 1 rotationarily movable in the direction of an arrow a, and a flying head slider 2 carrying a magnetic head 3. The magnetic head 3 is urged upwardly by air flow b so as to form a distance between the surface of the magnetic recording medium 1 and the magnetic head 3. The flying magnetic head apparatus also includes a suspension 5 made of a flexible material and held on a distal end of the flying head slider 2, and an arm 6 holding the suspension 5.
In this conventional magnetic head apparatus, as the magnetic recording medium 1 is rotated at a constant speed, an air flow b is created under the flying head slider 2 so that the flying head slider 2 is urged upwardly like a flying object. Meanwhile, since the suspension 5 is made of a flexible material and urges the magnetic head 3 against the magnetic recording medium 1, writing and reading are conducted, with a constant distance h between the magnetic head 3 and the head gap 4, due to the balance between the downward resilient force of the suspension 5 and the upward flying force of the flying head slider 2. The distance h between the magnetic head 3 and the magnetic recording medium 1 is a reference recording and reproducing characteristic. Since even a slight fluctuation of the space will be a cause for writing/reading error, it has been a common practice to minimize the distance with maintaining the followability to vertical vibrations while the magnetic recording medium surface is in rotation. For the time being, the distance of about 0.2 .mu.m has been realized.
As discussed above, in the conventional magnetic head apparatus, the distance h between the head gap 4 and the magnetic recording medium 1 is kept constant by utilizing the flying force of the flying head slider 2. However, reduction of the weight and size of the flying head slider 2 has already reached the limit range according to the present machining technology. Thus, further increase of the access speed is not achievable by the use of the conventional devices. In order to increase the access speed, the weight of the head slider must be reduced, because the access time is proportional to the square root of a movable member which includes the head slider.